Adapt channel maintenance test to not include directory count

After changing the `source/:project_name` to always pass the
request to the backend, the `count` attribute is not longer
part of the `directory` tag. This was only included by the frontend.

src/api/test/functional/channel_maintenance_test.rb

@@ -385,7 +385,7 @@ def test_large_channel_test
     assert_xml_tag tag: 'entry', attributes: { name: 'pack2.BaseDistro2.0_LinkedUpdateProject' }
     assert_xml_tag tag: 'entry', attributes: { name: 'pack2.linked.BaseDistro2.0_LinkedUpdateProject' }
     assert_xml_tag tag: 'entry', attributes: { name: 'patchinfo' }
-    assert_xml_tag tag: 'directory', attributes: { count: '4' }
+    assert_xml_tag tag: 'directory'
     # cleanup
     delete "/source/#{maintenance_yet_another_project}"
     assert_response :success